Earthquake Epicenter

Introduction
An earthquake epicenter is the point on the Earth's surface directly above the earthquake focus. The epicenter is the geographical location of the earthquake reported on television stations and written reports about earthquakes.

Earthquake block showing epicenter, Drawing by Myrna Martin

Earthquake block showing epicenter, Myrna Martin

Epicenter of an earthquake
The point where the rocks actually break is the earthquake focus. Large subduction zone earthquakes can break along a fault for hundreds of kilometer. The epicenter of these earthquakes is directly above where the earthquake actually started along the fault line.

Destruction at the epicenter
The amount of destruction at the epicenter of an earthquake is directly affected by its size and the depth where the rocks rupture. The epicenter of an earthquake is the same whether the rocks ruptured at 50 kilometers, 100 kilometers or even 300 kilometers beneath the Earth's surface.

Focus of an earthquake
Earthquakes with a focus of less than 70 kilometers are the most destructive. Therefore when listening to earthquake reports it is important to know the geographic location of the earthquake listed as the epicenter and the depth of the earthquake.

Studying epicenters
Seismologists use seismographs to study the earthquake epicenter. Using these epicenters they can discover the location of unknown faults and crustal plate boundaries.

Tokyo and Los Angeles on major fault zones
Scientists are especially concerned about epicenters of past large earthquakes in cities like Tokyo, Japan and Los Angeles, California. Both of these cities are located in major fault zones.

Northridge earthquake
The epicenter of the 1994 Northridge earthquake was in a large urban area and caused four billion dollars in damage. Prior to the earthquake scientists did not even know the fault existed and no small tremors gave warning of the impending disaster.

More Plate Tectonic Links

What is an Earthquake Find out what causes the Earth to shake, rattle and roll during an earthquake. 

Convergent Boundary There are two types of boundaries where plates converge. They produce great mountain ranges and large earthquakes.

Transform Boundary  These boundaries are found all around our ocean floors where oceanic plates are separating.

Pacific Plate The Pacific Plate is the largest plate on Earth. Great earthquakes and towering volcanoes surround the plate along the Pacific Ring of Fire.


Caribbean Plate This plate is small but very complex. It has a subduction zone, transform fault, and triple junction.

Earthquake Epicenter The epicenter of an earthquake is a point on the Earth's surface, not where the earthquake originates.

Plate Tectonics Find out lots of fascinating facts and interesting trivia on plate tectonics.

Kids Fun Science The links on our home page include information about volcanoes, science activities, plate tectonics, the rock cycle and much more.